Inborn metabolic disorders are genetic diseases which are uncommon each one, but together they are not. They are characterized by an enzimatic defect that blocks a metabolic pathway, producing specific signs and symptoms. The current article pretends be an updated guideline for their acute management which is based on: 1) Inmediate life support, hydroelectrolyte balance and sample procurement, 2) Avoiding the production of toxic endogenous metabolites and anabolism promotion, 3) The supplementation of substrates and 4) The removal of toxic substances. Their prompt suspicious, identification and treatment starting will be crucial for neurological prognosis and prevention of death.